19 21 ] Schmitt: The Marine Decapod Crustacea of California 273 



Hemigrapsus nudus (Dana) 

 Plate 47 



Pseudograpsus nudus Dana, Proe. Acad. Nat. Sci. Phila., 5, 249, 1851; 



Crust. U. S. Expl. Exped., 1, 335, 1852, pi. 20, fig. 7, 1855. 

 Eeterograpsus nudus Eathbun, E., The Fisheries and Fishery Industries of 



the TJ. S., see. 1, p. 765, 1884. 

 Brachynotus nudus Holmes, Oeeas. Papers Calif. Acad. Sci., 7, 81, 1900. 

 Hemigrapsus nudus Eathbun, H. A. E., 10, 189, 1904; Weymouth, Stanford 



Univ. Publ., Univ. Sen, no. 4, 62, pi. 14, fig. 42, 1910; Eathbun, Bull. 



U. S. Nat. Mus., 97, 267, pi. 69, 1918. 



Fig. 161. Hemigrapsus nudus, X % (after Dana). 



Characters. — Carapace posteriorly flat, smooth, and punctate, anteriorly eon- 

 vex, undulated, and furnished with small, scattered granules; front arcuate, 

 very slightly sinuous (front bilobed, median emargination shallow but compara- 

 tively broad). Chelipeds smooth, mottled above with small, round, red spots; in 

 the adult male there is a rounded lobe on the antero-internal angle of the merus, 

 and a patch of long hair on the inner surface of the hand. Ambulatory legs 

 naked, rather short; dactyls short, stout, scabrous, those of last pair less than 

 two and one-half times, often less than twice as long as wide, and up-turned 

 at the tip. 



Dimensions. — Type, female: length of carapace 22.3 mm., width 26.5 mm.; 

 male: length of carapace 22.6 mm., width 26.1 mm. "Width of carapace of the 

 Bay specimens ranged from 9 to 39 mm., the greater number being about 25 mm. 

 wide. 



Color. — Quite variable. It is generally of a mahogany red, but may be a 

 purplish tone, dark red, or red marbled with white. I have seen some specimens 

 with the upper side almost entirely white (Holmes). Ambulatory legs similar to 

 carapace; chelipeds lighter, marked with numerous small spots of darker red 

 (Weymouth). But amid all the variations of color the red spots on the chelipeds 

 remain an absolutely constant character so far as I can determine. Young speci- 

 mens present greater color variation than older ones (Holmes). 



Type Locality. — Puget Sound. 



Distribution. — From Sitka, Alaska, to Gulf of California (Eathbun). 



